JP7389253B2 - Correcting wafer edge asymmetry using polishing pad grooves - Google Patents

Description

TECHNICAL FIELD This disclosure relates to chemical mechanical polishing.

Integrated circuits are typically formed on a substrate by sequentially depositing conductive, semiconductor, or insulating layers on a silicon wafer. One manufacturing step includes depositing a filler layer on the non-planar surface and planarizing the filler layer. In certain applications, the fill layer is planarized until the top surface of the patterned layer is exposed. For example, a conductive filler layer can be deposited on a patterned insulating layer to fill trenches or holes in the insulating layer. After planarization, the portions of the conductive layer remaining between the raised patterns of the insulating layer form vias, plugs, and lines that provide conductive paths between thin film circuits on the substrate. In other applications, such as oxide polishing, the fill layer is planarized until a predetermined thickness remains on the non-planar surface. In addition, planarization of the substrate surface is typically required for photolithography.

Chemical mechanical polishing (CMP) is one generally accepted method of planarization. This planarization method typically requires mounting the substrate on a carrier or polishing head. The exposed surface of the substrate is typically positioned against a rotating polishing pad. The carrier head provides a controllable load to the substrate to press the substrate against the polishing pad. A polishing slurry is typically provided to the surface of a polishing pad.

One problem in polishing is non-uniformity in the polishing rate across the substrate. For example, edge portions of the substrate may be polished at a greater rate than central portions of the substrate.

In one aspect, a chemical mechanical polishing system includes a rotatable platen for holding a polishing pad, a rotatable carrier head for holding a substrate against a polishing surface of the polishing pad during a polishing process, and a controller. . The platen is rotatable by a motor and the polishing pad has a polishing control groove concentric with the axis of rotation of the polishing pad. The carrier is laterally movable across the polishing pad by a first actuator and rotatable by a second actuator. The controller controls the first actuator and the second actuator so that the first angular swath of the edge portion of the substrate is at an azimuthal position about the axis of rotation of the carrier head over a plurality of successive oscillations of the carrier head. , the first angular swath is above the polishing surface, and the second angular swath is above the polishing control groove when the second angular swath at the edge of the substrate is in that azimuthal position. The carrier head is further configured to synchronize the lateral vibration of the carrier head with rotation of the carrier head.

Implementations can include one or more of the following features.

The polishing pad may have a slurry supply groove, and the slurry supply groove may be narrower than the polishing control groove. The polishing pad may have a single polishing control groove surrounding a slurry supply groove, a single polishing control groove surrounded by a slurry supply groove, or exactly two polishing grooves with a slurry supply groove located between the two polishing control grooves. It may have a control groove. The controller may be configured to control the first actuator and the second actuator such that a first frequency of rotation of the carrier head is equal to an integer multiple of a second frequency of lateral vibration of the carrier head. .

In another aspect, a chemical mechanical polishing system includes a rotatable platen for holding a polishing pad, a rotatable carrier head for holding a substrate against a polishing surface of the polishing pad during a polishing process, and a controller. include. The platen is rotatable by a motor, the polishing pad has a polishing control groove concentric with an axis of rotation of the polishing pad, and the polishing groove has a plurality of arcuate segments. The carrier head is rotatable by an actuator. The controller controls the motor and actuator to rotate the second angular swath of the substrate edge portion when the first angular swath of the substrate edge portion is at an azimuthal position about the rotational axis of the carrier head over a plurality of successive rotations of the carrier head. The angular swath of is over the area of the polishing surface between the arcuate segments, and when the second angular swath of the edge portion of the substrate is in its azimuthal position, the second angular swath is over the arcuate segment of the polishing control groove. The rotation of the platen is configured to synchronize with the rotation of the carrier head, as shown in FIG.

Implementations can include one or more of the following features.

The arcuate segments may be equiangularly spaced about the axis of rotation of the platen. Arcuate segments can have equal lengths. Each arcuate segment can define an arc of 10 to 45 degrees. There are 4 to 20 arcuate segments. The polishing pad may further include a slurry supply groove, and the slurry supply groove may be thinner than the polishing control groove. The controller is configured to control the motor and actuator such that the first frequency of rotation of the carrier head is an integer multiple of the second frequency of rotation of the platen.

Improvements may include, but are not limited to, one or more of the following: Non-uniformities, particularly angularly asymmetric non-uniformities near the edges of the substrate, can be reduced.

The details of one or more implementations are set forth in the accompanying drawings and the description below. Other aspects, features, and advantages will be apparent from the description and drawings, and from the claims.

1 is a schematic cross-sectional view of a chemical mechanical polishing system including a polishing pad with polishing control grooves. FIG. 1 is a schematic cross-sectional view of a radial cross section of a polishing pad having both slurry supply grooves and polishing control grooves. FIG. 1 is a schematic top view of an exemplary chemical mechanical polishing apparatus showing the carrier head in different lateral positions; FIG. 1 is a schematic top view of an exemplary chemical mechanical polishing apparatus showing the carrier head in different lateral positions; FIG. 2 is an exemplary graph of substrate position on a platen versus time. 1 is a schematic top view of a chemical mechanical polishing apparatus showing the carrier head in different lateral positions; FIG. 1 is a schematic top view of a chemical mechanical polishing apparatus showing the carrier head in different lateral positions; FIG. FIG. 3 is a schematic top view of another embodiment of a chemical mechanical polishing apparatus showing the carrier head in different lateral positions. FIG. 3 is a schematic top view of another embodiment of a chemical mechanical polishing apparatus showing the carrier head in different lateral positions.

Like reference numbers and designations in the various drawings indicate similar elements.

In chemical mechanical polishing, the removal rate at the edge of the substrate can be different than the removal rate at the center of the substrate. Furthermore, the polishing rate near the edge of the substrate need not be uniform along the circumference. This effect can be called "edge asymmetry." To address the resulting substrate thickness irregularities, the substrate can be transported to a specialized polishing "touch-up" tool to polish localized areas on the substrate. Such tools can be used to correct substrate edge asymmetries. For example, after the polishing process is complete, thicker regions at the edges of the substrate can be locally polished to provide a substrate of uniform thickness. However, the throughput of such touch-up tools is low, and touch-up tools add additional cost and footprint to the manufacturing facility.

One technique that can address this problem is to synchronize the rotation of the carrier head with the lateral movement of the carrier head or rotation of the platen to preferentially place over-polished areas of the substrate onto the polishing control grooves. be. This approach can reduce non-uniformities in the polished substrate, particularly edge asymmetry. Furthermore, this technique can be applied to the chemical-mechanical polishing tool itself, thus avoiding large capital costs and installation of new tools.

FIG. 1 shows an example polishing station of a chemical mechanical polishing system 20. As shown in FIG. Polishing system 20 includes a rotatable disk-shaped platen 24 upon which a polishing pad 30 is disposed. Platen 24 is rotatably operable about axis 25 . For example, motor 26 may rotate drive shaft 28 to rotate platen 24 . Polishing pad 30 may be a two-layer polishing pad with an outer polishing layer 32 and a softer backing layer 34. Outer polishing layer 32 has a polishing surface 36 .

Polishing system 20 can include a supply port or integrated supply rinse arm 92 for dispensing a polishing liquid 94, such as a polishing slurry, onto polishing pad 30. Polishing system 20 may include a pad conditioner apparatus 40 with a conditioning disc 42 to maintain the surface roughness of polishing surface 36 of polishing pad 30 . Conditioning disc 42 can be positioned at the end of an arm 44 that can swing to sweep disc 42 radially across polishing pad 30.

Carrier head 70 is operable to hold substrate 10 against polishing pad 30 . Carrier head 70 is suspended from support structure 50, such as a carousel or track, and is connected to carrier head rotation motor 56 by drive shaft 58 such that carrier head can rotate about axis 55. The carrier head 70 may vibrate laterally, for example, on a slider on a carousel, by movement along a track, or by rotational vibration of the carousel itself.

Carrier head 70 includes a housing 72, a substrate backing assembly 74 including a base 76 and a flexible membrane 78 defining a plurality of pressurizable chambers 80, a gimbal mechanism 82 (which may be considered part of assembly 74), a loading chamber 84, a retaining ring assembly 100, and an actuator 122.

Housing 72 may be generally circular in shape and may be connected to drive shaft 58 to rotate therewith during polishing. There may be a passage (not shown) extending through the housing 72 for pneumatic control of the carrier head 100. Substrate backing assembly 74 is a vertically movable assembly located below housing 72. Gimbal mechanism 82 allows base 76 to be gimballed relative to housing 72 while preventing lateral movement of base 76 relative to housing 72. Loading chamber 84 is disposed between housing 72 and base 76 to apply a load, ie, downward pressure or weight, to base 76 and thus to the substrate backing assembly. The vertical position of substrate backing assembly 74 relative to the polishing pad is also controlled by loading chamber 84. The lower surface of flexible membrane 78 provides a mounting surface for substrate 10.

In some implementations, substrate backing assembly 74 is not a separate component movable relative to housing 72. In this case, chamber 84 and gimbal 82 are not required.

With continued reference to FIG. 1, polishing pad 30 has at least one polishing control groove 102 formed in polishing surface 36. Each polishing control groove 102 is a recessed area of the polishing pad 30. Each polishing control groove 102 may be an annular groove, for example a circular groove, and may be concentric with the rotation axis 25 of the platen 24. Each polishing control groove 102 provides an area of polishing pad 30 that does not contribute to polishing.

The walls of polishing control groove 102 are perpendicular to polishing surface 36. Polishing control groove 102 can have a rectangular or U-shaped cross section. Polish control grooves 102 may be 10 to 80 mils deep, such as 10 to 60 mils deep.

In some embodiments, the pad 30 has polishing control grooves disposed near the outer edge of the polishing pad 30, such as within 15%, such as within 10%, such as within 5% (in radius) of the outer edge. 102a. For example, groove 102 may be located at a radial distance of 14 inches from the center of a platen having a diameter of 30 inches.

In some implementations, the pad 30 has a polishing control groove 102b located near the center of the polishing pad 30, e.g., within 15%, e.g., within 10% (in radius) of the center or axis of rotation 25. include. For example, groove 102b may be located at a radial distance of 1 inch from the center of a platen having a diameter of 30 inches.

In some implementations, pad 30 includes only polishing control grooves 102a located near the outer edge of polishing pad 30 (see FIGS. 3A and 3B). In this case, there may be only one control polishing groove 102a near the outer edge of polishing pad 30. In some implementations, pad 30 includes only polishing control grooves 102b located near the center of polishing pad 30. In this case, there may be only one control polishing groove 102b near the center of polishing pad 30. In some implementations, the pad 30 includes a first polishing control groove 102a located near the edge of the polishing pad 30 and a first polishing control groove 102b located near the center of the polishing pad 30. (see Figure 1). In this case, there may be exactly two polishing grooves 102 on the polishing surface.

The polishing control groove 102 is sufficiently wide such that positioning a portion of the substrate 10 over the groove substantially reduces the polishing rate in that portion. In particular, for edge correction, the groove 102 is formed by an annular band at the edge of the substrate, for example a band of at least 3 mm wide, such as a band of 3 to 15 mm width, such as a band of 3 to 10 mm width. , is wide enough to reduce the polishing rate. Polishing control groove 102 may be 5 to 50 millimeters wide, for example 10 to 20 millimeters wide.

When substrate 10 is placed on polishing surface 36 of polishing pad 30, polishing surface 36 contacts substrate 10 to polish substrate 10 and material removal occurs. On the other hand, when the edge of the substrate 10 is disposed over the polishing control groove 102, there is no contact or polishing of the edge of the substrate 10 such that removal occurs. Optionally, grooves 102 can provide a conduit for polishing slurry to pass through without abrading substrate 10.

Referring now to FIG. 2, polishing pad 30 can also include one or more slurry supply grooves 112. Slurry supply groove 112 may be an annular groove, for example a circular groove, and may be concentric with polishing control groove 102. Alternatively, the slurry supply grooves can have another pattern, such as rectangular crosshatch, triangular crosshatch, etc. The slurry feed groove has a width of between about 0.015 and 0.04 inches (0.381 and 1.016 mm), e.g., 0.20 inches, and a width of between about 0.09 and 0.24 inches, e.g. It can have a pitch of 0.12 inches.

Slurry supply groove 112 is narrower than polishing control groove 102 . For example, the slurry supply groove 112 can be narrowed by at least a third, such as at least a sixth, such as from 6 to 100 times narrower. Slurry supply grooves 112 may be uniformly spaced across polishing pad 30. Polishing control groove 102 can have a shallower, similar, or greater depth than slurry supply groove 112. In some implementations, polishing control groove 102 is the only groove on the polishing pad that is wider than slurry supply groove 112. In some implementations, polishing control grooves 102a and 102b are the only grooves on the polishing pad that are wider than slurry supply grooves 112.

Referring now to FIG. 3A, during at least a portion of the polishing operation, e.g., a first duration, the substrate 10 is rotated so that the central portion 12 of the substrate 10 and the edge portion 14 of the substrate 10 are both aligned with the polishing surface of the polishing pad 30. 36 may be placed in a first position or a first range of positions. Therefore, nowhere on the substrate 10 overlaps the polishing control groove 102. Although a portion of the substrate 10 overlaps with the slurry supply grooves 112, the slurry supply grooves 112 are relatively closely spaced, and the relative movement averages out the effect on the polishing rate.

Referring to FIG. 3B, during at least a portion of the polishing operation, such as a second duration, the substrate 10 is polished such that the central portion 12 of the substrate 10 is polished by the polishing surface 36 and the area of the edge portion 14 of the substrate 10 is polished by the polishing surface 36. 14a may be placed above the polishing control groove 102. During the second duration, the substrate 10 may be held laterally fixed in the second position. Thus, the central portion 12 of the substrate 10 is polished during the second duration, while the region 14a of the edge portion 14 of the substrate 10 located above the polishing control groove 102 is not polished. Since a portion of the edge portion 14 (indicated by 14b) remains above the polishing surface 36, the edge portion 14 will still be polished to some extent, but due to the lack of polishing in area 14a, the central portion 12 polished at a lower rate than Although a portion of the substrate 10 overlaps with the slurry supply grooves 112, the slurry supply grooves 112 are relatively closely spaced, and the relative movement averages out the effect on the polishing rate.

The particular amount of time that region 14a of edge portion 14 remains above polishing control groove 102 depends on the frequency and magnitude of the vibration and the dimensions of the groove and substrate. A controller 90 (see FIG. 1) can control the motors 25, 56 to control the rotational speed of the platen 20 and the carrier head 70, and can control actuators coupled to the support to control the rotation speed of the carrier head 70. The frequency and magnitude of the lateral vibrations can be controlled.

Referring to FIG. 4, the substrate can be moved in a vibration pattern in which the substrate makes a single sweep for a first duration T ₁ (t ₀ -t ₁ ). In some implementations, at the end of the first duration, the substrate is positioned such that the central portion 12 of the substrate 10 is disposed over the polishing region of the polishing pad 30 and the edge portion 14 of the substrate 10 is positioned in the polishing control groove 102. in the overlying and held position for a second duration T ₂ (t ₁ -t ₂ ). In this case, the frequency of vibration is 1/(T ₁ +T ₂ ).

The ratio of the first duration T ₁ and the second duration T ₂ can be selected to reduce the polishing rate of the edge portion 14 by a desired amount compared to the central portion 12. For example, the ratio T ₁ /T ₂ can be selected to achieve a desired average polishing rate at the edges, eg, the same average polishing rate as the central portion 12.

Referring to FIG. 5A, as discussed above, the substrate may have asymmetry. For example, the edge portion 14 of the substrate 10 can have a first angular swath 16a and a second angular swath 16b, each having a different thickness. To compensate for the edge asymmetry of the substrate 10, the controller 90 configures the edge portion 14 of the substrate 10 such that different swaths of the edge portion 14 are either over the polishing control groove 102 or over the polishing area of the polishing pad 30. Movement of the carrier head 70 can be caused. This can be done by synchronizing the vibration of carrier head 70 and the rotation of carrier head 70. For example, each second duration T ₂ corresponds to the time that the second angular swath 16b is over the polishing control groove 102.

For example, assuming that the first angular swath 16a is thicker than the second angular swath 16b, the first angular swath 16a of the substrate 10 is at a predetermined azimuthal position 18 about the axis of rotation 55 of the carrier head 70. The lateral position of the carrier head and the rotation of the carrier head can then be synchronized such that the carrier head 70 can be positioned such that the first angular swath 16a is over the polishing portion 104 of the polishing pad 30. Azimuth position 18 may be the position on carrier head 70 furthest from polishing pad rotation axis 25. Similarly, azimuth position 18 may be on a line passing through axis of rotation 25 of polishing pad 30 and axis of rotation 55 of carrier head 70.

Referring to FIG. 5B, as the carrier head 70 rotates, the second angular swath 16b moves toward the predetermined azimuthal position 18. The lateral position of carrier head 70 and the rotation of carrier head 70 are such that by the time second angular swath 16b is at a predetermined azimuthal position 12 about axis of rotation 55 of carrier head 70, second angular swath 16b The carrier head 70 can be synchronized so that it moves laterally so that it is above the polishing control groove 102. As a result, first angular swath 16a is polished at a higher rate than second angular swath 16b. This makes it possible to provide a more uniform substrate 10, and in particular to reduce edge asymmetry.

For synchronization, controller 90 controls motor 26 and actuator 58 such that a first frequency of rotation of the carrier head is equal to an integer multiple of a second frequency of lateral vibration of the carrier head. , may be configured. For example, the first frequency of rotation can be equal to the second frequency. Note that this synchronization must be maintained fairly accurately. The mismatch results in a precession of the angular swath for a given azimuthal position 18, thus negating the effectiveness of edge asymmetry correction.

Although FIG. 4 shows that the substrate is held in place for a second duration _T2 , this is not necessary. Even as the carrier head 70 continuously sweeps back and forth across the polishing pad 30 (e.g., the radial position is a trigonometric or sinusoidal function of time), the second angular swath 16b remains over the polishing control groove 102. There can be a period of time.

Furthermore, while the above discussion focuses on a polishing pad with a single polishing control groove 102a near the outer periphery of the polishing pad, similar principles apply with polishing grooves 120b located near the center of the polishing pad. , can also be applied when a second angular swath 16b, which would otherwise be over-polished, is placed over the polishing control groove 102b to reduce the polishing rate of that swath. .

Referring to FIGS. 6A and 6B, in some embodiments, polishing control groove 102 may include multiple arcuate segments 132 (rather than being a continuous circle). There may be between 4 and 20 arcuate segments 132. The arcuate segments 132 may be equiangularly spaced about the platen's axis of rotation 25. Arcuate segments 132 can have equal lengths. Each arcuate segment can define an arc of 15 to 90 degrees.

Controller 90 can synchronize the rotation of carrier head 70 with the rotation of platen 24 and polishing pad 30 (indicated by arrow C) to reduce the polishing rate in areas of the substrate that are being overpolished. In this configuration, no lateral sweep of the carrier head 70 is required to achieve edge asymmetry compensation.

For example, if the first angular swath 16a of the edge portion 14 of the substrate 10 is thicker than the second angular swath 16b, then the first angular swath 16a overlies the sections 130 of the polishing surface 36 between the arcuate segments 132 of the grooves. Polishing can be started in this state. As both polishing pad 30 and carrier head 70 rotate, second angular swath 16b moves outwardly toward the radius in which the arcuate segments are located. The controller 90 controls the rotation of the carrier head 70 and the polishing pad such that the second angular swath 16b is over one of the arcuate segments 132 when the second angular swath 16b reaches the radial position of the groove 102. 30 rotations can be synchronized. As a result, the first angular swath 16a can be polished at a higher rate than the second angular swath 16b, thereby reducing edge asymmetry and improving uniformity.

To achieve synchronization, the controller 90 may be configured to control the motors 26, 56 such that a first frequency of rotation of the carrier head is equal to an integer multiple of a second frequency of rotation of the platen. . For example, the first frequency of rotation can be equal to N, where N is a divisor of the number of arcuate segments 132. In some implementations, N is equal to 1. Note that this synchronization must be maintained fairly accurately. The mismatch results in a precession of the angular swath for a given azimuthal position 18, thus negating the effectiveness of edge asymmetry correction.

As used herein, the term substrate can include, for example, product substrates (eg, including multiple memory or processor dies), test substrates, bare substrates, and gating substrates. The substrate may be at various stages of integrated circuit manufacturing; for example, the substrate may be a bare wafer or may include one or more deposited and/or patterned layers. The term substrate can include circular disks and rectangular sheets.

Controller 90 may include a special purpose microprocessor, such as an ASIC, or a conventional computer system executing a computer program stored on a non-volatile computer-readable medium. Controller 90 may include a central processing unit (CPU) and memory containing associated control software.

The polishing system and polishing method described above can be applied to various polishing systems. Either the polishing pad, the carrier head, or both can move to provide relative motion between the polishing surface and the substrate. The polishing pad can be a circular (or other shaped) pad secured to the platen. The abrasive layer can be a standard (eg, filled or unfilled polyurethane) abrasive, a soft material, or a fixed abrasive. Although relative positional terms are used, it is understood that the polishing surface and substrate may be held in a perpendicular orientation or other orientations.

Certain embodiments of the invention have been described. Other embodiments are within the scope of the following claims. For example, the acts recited in the claims may be performed in a different order and still achieve desirable results.

Claims (19)

a rotatable platen for holding a polishing pad, the platen being rotatable by a motor, the polishing pad having a polishing surface and a polishing control groove concentric with an axis of rotation of the polishing pad; platen and
a rotatable carrier head for holding a substrate against the polishing surface of the polishing pad during a polishing process, the carrier head being laterally movable by a first actuator across the polishing pad; a carrier head rotatable by a second actuator;
controlling the first actuator and the second actuator to adjust a first angle of an edge portion of the substrate over a plurality of successive oscillations of the carrier head to compensate for edge asymmetry of the substrate; When the swath is at an azimuthal position about the axis of rotation of the carrier head, the first angular swath is above the polishing surface and the second angular swath of the edge portion of the substrate is at the azimuthal position. a controller configured to synchronize lateral vibration of the carrier head with rotation of the carrier head such that when in position, the second angular swath is over the polishing control groove;
Chemical-mechanical polishing system with The system of claim 1, wherein the polishing pad further comprises a slurry supply groove. 2. The system of claim 1 , wherein the polishing control groove provides an area of the polishing pad that does not contribute to polishing, and wherein the polishing control groove is between 5 and 50 millimeters in width. 3. The system of claim 2 , wherein the polishing pad has a single polishing control groove surrounding the slurry supply groove. 3. The system of claim 2 , wherein the polishing pad has a single polishing control groove surrounded by the slurry supply groove. 3. The system of claim 2 , wherein the polishing pad has exactly two polishing control grooves, and the slurry supply groove is disposed between the two polishing control grooves. The controller controls the first actuator and the second actuator such that a first frequency of rotation of the carrier head is equal to an integer multiple of a second frequency of lateral vibration of the carrier head. 2. The system of claim 1, wherein the system is configured to. A rotatable platen for holding a polishing pad, the platen being rotatable by a motor, the polishing pad having a polishing surface and a polishing control groove concentric with an axis of rotation of the polishing pad. , the polishing control groove having a plurality of arcuate segments;
a rotatable carrier head for holding a substrate against the polishing surface of the polishing pad during a polishing process, the carrier head being rotatable by an actuator;
controlling the motor and the actuator so that over a plurality of successive rotations of the carrier head, a first angular swath of the edge portion of the substrate is at an azimuthal position about an axis of rotation of the carrier head; a second angular swath overlies the area of the polishing surface between arcuate segments, and when a second angular swath of the edge portion of the substrate is in the azimuthal position, the second angular swath overlies the polishing surface; a controller configured to synchronize rotation of the platen with rotation of the carrier head over an arcuate segment of a control groove;
Chemical-mechanical polishing system with 9. The system of claim 8, wherein the arcuate segments are equiangularly spaced about an axis of rotation of the platen. 9. The system of claim 8, wherein the arcuate segments have equal lengths. 9. The system of claim 8, wherein each arcuate segment defines an arc of 5 to 15 degrees. 9. The system of claim 8, wherein there are 4 to 20 arcuate segments. 9. The system of claim 8, wherein the polishing pad further comprises a slurry supply groove. 14. The system of claim 13, wherein the slurry supply groove is narrower than the polishing control groove. 9. The controller is configured to control the motor and the actuator such that a first frequency of rotation of the carrier head is an integer multiple of a second frequency of rotation of the platen. system described in. A method for chemical mechanical polishing, the method comprising:
rotating a polishing pad around an axis of rotation;
arranging a substrate so as to abut the polishing pad having a polishing surface and a polishing control groove concentric with the rotation axis;
To compensate for edge asymmetry of the substrate, over a plurality of successive oscillations of the polishing pad, a first edge portion of the substrate is disposed above the polishing surface and a second edge portion of the substrate is vibrating the substrate laterally across the polishing pad and rotating the substrate so that it is disposed over the polishing control groove;
method including. 17. The method of claim 16, wherein a first frequency of rotation of the substrate is equal to an integer multiple of a second frequency of lateral vibration of the substrate. A method for chemical mechanical polishing, the method comprising:
rotating a polishing pad around an axis of rotation;
arranging the substrate so as to abut the polishing pad having a polishing surface and a polishing control groove concentric with the rotation axis and having a plurality of arcuate segments;
To compensate for edge asymmetry of the substrate, over a plurality of successive oscillations of the polishing pad, a first edge portion of the substrate is disposed over the portion of the polishing surface between the arcuate segments, and the substrate rotating the substrate such that a second edge portion of the polishing control groove is disposed over the arcuate segment of the polishing control groove;
method including. 19. The method of claim 18, wherein the first frequency of rotation of the substrate is equal to an integer multiple of the second frequency of rotation of the polishing pad.

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